I've got the headlight modulator, the brake light modulator, an LED backplate behind the license plate that flashes red with the brake light, and reflective rim tape.
In the near future, I'll be putting six flush-mount bolt LEDs in the front, hooked to the headlight such that they're on whether the low beam or high beam is on (and flashing when the high beam flashes). Four of them will face forward for better lighting, and two of them will light the front wheel well, so people know they're looking at a cycle, and not a car.
The headlight modulator has saved me more times than I can count... people in cars just aren't looking for motorcycles or scooters (especially when turning left from a parking lot into traffic, their attention is divided between looking for oncoming traffic from the left, and from the right, and trying to time it so they don't get hit), but when they see that 6500 K headlight flashing, they know something is coming.
The brakelight modulator has saved me a few times, too. I keep an eye on my rear view mirrors, and pull in the brake to flash the brake light a few times... three times now, people have locked them up because they just didn't "see" me until they saw the flashing light. Most people stop well back from me when I flash... I guess they think it's a cop bike, since all the cop bikes have the same thing.
Of course, it helps that the brake light is an LED with a lens on the end of it that directs a very bright red light right into the eyes of approaching drivers. It's bright enough that you can see it reflecting off things a block back. It's got LEDs around the periphery to give a wide dispersal of red light, as well.